Subacute Inclusion Encephalitis: A Clinical and Pathological Review

Subacute inclusion encephalitis has been reported most frequently from Western Europe; only 16 cases have been described in North America. During the past eight years the authors have encountered 14 cases in the Toronto area, and histological confirmation has been obtained in seven of these. The disease most often presents as a combination of progressive personality and intellectual deterioration combined with myoclonic seizures or drop attacks and focal neurological deficits, although extrapyramidal symptoms or evidence of raised intracranial pressure may also occur. At the time of the initial presentation the EEG was characteristic in only nine of the 14 cases, but a first-zone rise in the colloidal gold curve was present in all cases in which it was carried out. From the pathological features of the disease, as described, and its absence of familial occurrence, it is concluded that a viral origin is most probable, although its rarity and predilection for a particular age group are unusual.